It is known to fabricate structural parts for buildings, tanks or the like from concrete using modular stay-in-place forms (also known as “form-works”). Such structural parts may include walls, ceilings or the like. Examples of such modular stay in place forms include those described US patent publication No. 2005/0016103 (Piccone) and PCT publication No. WO96/07799 (Sterling). A representative drawing depicting a partial form 28 according to one prior art system is shown in top plan view in FIG. 1. Form 28 includes a plurality of wall panels 30 (e.g. 30A, 30B, 30D), each of which has an inwardly facing surface 31A and an outwardly facing surface 31B. Each of panels 30 includes a terminal male T-connector component 34 at one of its transverse, vertically-extending edges (vertical being the direction into and out of the FIG. 1 page) and a terminal female C-connector component 32 at its opposing vertical edge. Male T-connector components 34 slide vertically into the receptacles of female C-connector components 32 to join edge-adjacent panels 30 to form a pair of substantially parallel wall segments (generally indicated at 27, 29). Depending on the needs for particular wall segments 27, 29, different panels 30 may have different transverse dimensions. For example, comparing panels 30A and 30B, it can be seen that panel 30A has approximately ¼ of the transverse length of panel 30B.
Form 28 includes support panels 36 which extend between, and connect to each of, wall segments 27, 29 at transversely spaced apart locations. Support panels 36 include male T-connector components 42 slidably received in the receptacles of female C-connector components 38 which extend inwardly from inwardly facing surfaces 31A or from female C-connector components 32. Form 28 incorporates tensioning panels 40 which extend between panels 30 and support panels 36 at various locations within form 28. Tensioning panels 40 include male T-connector components 46 received in the receptacles of female C-connector components 38.
In use, form 28 is assembled by slidable connection of the various male T-connector components 34, 42, 46 in the receptacles of the various female C-connectors 32, 38. Liquid concrete is then poured into form 28 between wall segments 27, 29. The concrete flows through apertures (not shown) in support panels 36 and tensioning panels 40 to fill the inward portion of form 28 (i.e. between wall segments 27, 29). When the concrete solidifies, the concrete (together with form 28) may provide a structural component (e.g. a wall) for a building or other structure.
One well-known problem with prior art systems is referred to colloquially as “unzipping”. Unzipping may refer to the partial or complete separation of connector components from one another due to the weight and/or outward pressure generated by liquid concrete when it is poured into form 28. By way of example, unzipping may occur at connector components 32, 34 between panels 30. FIG. 2 schematically depicts the unzipping of a prior art connection 50 between male T-connector component 34 and corresponding female C-connector component 32 at the edges of a pair of edge-adjacent panels 30. The concrete (not explicitly shown) on the inside 51 of connection 50 exerts outward forces on panels 50 (as shown at arrows 52, 54). These outward forces tend to cause deformation of the connector components 32, 34. In the FIG. 2 example illustration, connector components 32, 34 exhibit deformation in the region of reference numerals 56, 58, 60, 62, 64, 68. This deformation of connector components 32, 34 may be referred to as unzipping.
Unzipping of connector components can lead to a number of associated problems. In addition to the unattractive appearance of unzipped connector components, unzipping can lead to separation of male connector components 34 from female connector components 32. To counteract this problem, prior art systems typically incorporate support panels 36 and tensioning panels 40, as described above. However, support panels 36 and tensioning panels 40 represent a relatively large amount of material (typically plastic) which can increase the overall cost of form 28. Furthermore, support panels 36 and tensioning panels do not completely eliminate the unzipping problem. Notwithstanding the presence of support panels 36 and tensioning panels 40, in cases where male connector components 34 do not separate completely from female connector components 32, unzipping of connector components 32, 34 may still lead to the formation of small spaces (e.g. spaces 70) or the like between connector components 32, 34. Such spaces can be difficult to clean and can represent regions for the proliferation of bacteria or other contaminants and can thereby prevent or discourage the use of form 28 for particular applications, such as those associated with food storage or handling or other applications for which sanitary conditions or the like are desirable. Such spaces can also permit the leakage of fluids (e.g. liquids and/or gasses) between the inside 51 and outside 53 of panels 30 (e.g. between panels 30 and the concrete lined by panels 30). In some cases, fluids can leak through the concrete contained in the form and through the panels on the opposing side of the structure. Fluid leakage can prevent or discourage the use of form 28 for applications where it is desirable that form 28 be impermeable to liquid and/or gas. Such leakage can also lead to unsanitary conditions on the inside of form 28. The leakage of fluids to spaces between panels 30 and the concrete lined by panels 30 can cause panels 30 to separate further from the concrete they contain, exacerbating other issues, such as the cleanliness, sanitariness, or fluid impermeability of the form-work and/or the resulting structure.
There is a general desire to provide modular form components and connections therefor which overcome or at least ameliorate some of the drawbacks with the prior art.